1. FIELD OF THE INVENTION
This invention relates to a motion picture film with a sound track and to a process for producing the same.
2. DESCRIPTION OF THE PRIOR ART
A photographic material for motion picture film comprises a tape-like transparent plastic film and a coating of a silver halide photographic emulsion thereon. The motion picture film is produced by forming photographic images continuously on the photographic material at certain intervals so as to avoid the duplication of the individual images. Usually, a magnetic recording track and/or an optical recording track in the form of a narrow band is provided along the edge of one end in the widthwise direction, and sound recording is performed so that when the motion picture film is projected and reproduced the sound is synchronously reproduced with the reproduction of a series of continuous images (more precisely, the images are intermittent but appear continuous to the eye).
The magnetic sound recording track is provided on a motion picture film or the photographic emulsion layer of a photographic material for producing the motion picture film in view of the advantage of its handling in manufacturing or projecting apparatus. However, when the sound track is provided on the photographic emulsion layer of the photographic material, adhesion between the emulsion layer and the sound track is poor, and sometimes the sound track drops off from the film.
Attempts have therefore been made to remedy this defect, for example, by (1) exposing the plastic film of the motion picture film and coating a coating solution for forming a magnetic recording track directly on the exposed plastic film, by (2) providing a layer of an undercoat only on the part of the emulsion layer on which the sound track is to be formed, the undercoat serving to increase adhesion between the emulsion layer and the sound track, or (3) by changing the type of a binder in the sound track forming coating solution. However, methods (1) and (2) are troublesome and timeconsuming because of the necessity for partial exfoliation of the photographic layer or the provision of an undercoat layer, and method (3), relying on the selection of the binder, has not provided sufficient bonding effects.
Typical prior art motion picture films are disclosed in French Pat. No. 7046632 (corresponding to Japanese patent publication No. 23364/1974), French Pat. No. 7101772 (corresponding to Japanese patent publication No. 11565/1974), and French Pat. No. 7118200 (corresponding to U.S. Pat. No. 3,704,167).